One of the major improvements in metal machining has been the development of electronically controlled machining equipment (CNC). The demands for higher accuracy and performance brought about by this technology has fostered the development of Linear Motion Systems. These systems generally have specifically designed rails which are fastened onto the machine tool bed or table and guides or carriages which traverse the rail. These carriages generally have ball or roller bearings with appropriate races incorporated therein. The configuration of the carriages/rails being notched or having undercuts on which the bearings ride. The linear bearing system yielding significantly greater accuracy of traverse and loading capability at reduced power consumption because of reduced friction in comparison to the now obsolete slide rail configuration.
Although dimensions and configuration of rails and carriages vary depending upon manufacturer and loading demands they all use rubber wipers to cleanse the rail of metal cuttings to prevent the same from entering into the carriage bearings as the carriage traverses the rail. As is well known, such metal cuttings contamination effectively ruins bearing systems.
As stated earlier, the configuration of the matched rail-carriage systems have undercuts in the rail on which the bearings ride. The rubber wipers have a similar configuration so as to conform to the rail. In the current art, the rubber wipers are held in place by separate like configured metal place which is fastened to the carriage to support the rubber wiping lips which are in contact with the rail.
Most linear bearing carriages are used in multiples to balance a compound, for example on a lathe. Both ends of the carriages have wipers located thereon to wipe the rails as the carriages traverse the same. Removal of the outer wiper is relatively easy because the carriages working in tandem can be moved to the end of the rail where the wiper assembly can readily be slid off the end of the rail. The wiper on the inner end of the carriages presents the problem wherein the compound or other machine component that is located thereon must be removed from the carriages before the carriages can be removed from the rail to provide access to the inner wiper. The solution to this problem has been the use of elastomer wipers with separate backing plates which are bolted to the carriage through the elastomer wiper for replacement. The backing plate must then be precisely aligned over the wiper and fastened to the carriage face. Extreme care is required in this procedure to prevent distortion and tearing of the wiper lips.
Bonding metal backing plates to the elastomer in a mold for precise geometry eliminates that problem but because such wipers with bonded metal backing plate which cannot be removed over the rail but rather only from an end of a rail. Thus the machine must be disassembled so that the worn metal plate bonded wiper can be removed from the rail and replaced. Such removal is costly, in many instances requiring over fifty hours of non-production down time to remove/replace wipers. Replacement of the wiper must be done on a routine basis depending upon the extent of the machine's usage and type of metals being cut. Not doing so assures the costly replacement of rails and bearing carriages as accuracy of machining decreases and friction increases because of wear to the bearings and rails.